Secondary air control valve

ABSTRACT

A secondary air control valve connected to an exhaust system includes a passage forming member and a valve mechanism. The passage forming member includes a container unit and a plurality of fins. The container unit that defines therein an exit cavity and an exit passage. The plurality of fins projects from the container unit into the exit cavity such that the plurality of fins collides with counter-flow exhaust gas that counter-flows in a direction from the exit passage to the exit cavity through the first opening. The plurality of fins divides the exit cavity into a plurality of cavities, in which counter-flow exhaust gas forms a plurality of vortex flows.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by reference Japanese Patent Application No. 2010-65354 filed on Mar. 22, 2010.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a secondary air control valve that supplies secondary air to an exhaust system of an internal combustion engine.

2. Description of Related Art

JP-A-2005-520097 describes a secondary air control valve. The secondary air control valve is connected to an exhaust system in order to supply secondary air to an exhaust system, through which exhaust gas flows. Sometimes, exhaust gas may counter-flow in a direction from the exhaust system to an internal passage of the secondary air control valve. The above counter-flow exhaust gas has temperature higher than temperature of secondary air, and may include unwanted components. For example, exhaust gas may include a corrosive component, or an adhesive component.

In order to block the flow of counter-flow exhaust gas, a conventional technique proposes a configuration, in which a passage downstream of the secondary air control valve has a tortuous shape. Also, the conventional technique proposes a baffle plate that blocks counter-flow exhaust gas. Further, the conventional technique proposes a heat dissipation fin that is provided to a member that defines the downstream passage.

In the configuration of the conventional technique, it may be impossible to effectively remove heat from counter-flow exhaust gas disadvantageously. In other words, because the tortuous passage has a U shape, the heat of counter-flow exhaust gas is difficult to be transmitted to a case member that defines the tortuous passage disadvantageously. As a result, movable components of the secondary air control valve may have excessively high temperature.

Also, in the tortuous passage of the conventional technique, because counter-flow exhaust gas flows along a single route, it may be impossible to sufficiently weaken the flow of counter-flow exhaust gas disadvantageously.

Furthermore, the tortuous passage of the conventional technique also erroneously generates resistance to the regular flow of secondary air, which is directed to the exhaust system, similarly to resistance to counter-flow exhaust gas disadvantageously. In other words, the tortuous passage of the conventional technique may erroneously apply pressure drop to the regular flow of secondary air directed to the exhaust system, which pressure drop is equivalent to pressure drop applied to counter-flow exhaust gas. As a result, it has been difficult to supply secondary air of a large flow amount.

Also, in the conventional technique, because a baffle plate is additionally provided, the number of components is increased disadvantageously.

SUMMARY OF THE INVENTION

The present invention is made in view of the above disadvantages. Thus, it is an objective of the present invention to address at least one of the above disadvantages.

To achieve the objective of the present invention, there is provided a secondary air control valve connected to an exhaust system, which allows exhaust gas to flow therethrough, wherein the secondary air control valve supplies secondary air to the exhaust system, the secondary air control valve including a passage forming member and a valve mechanism. The passage forming member defines a passage, through which secondary air is supplied to the exhaust system. The valve mechanism is provided in the passage. The passage forming member includes a container unit and a plurality of fins. The container unit that defines therein an exit cavity and an exit passage. The exit cavity is provided between the valve mechanism and the exhaust system. The exit passage has a first opening communicated with the exit cavity and has a second opening communicated with the exhaust system. The plurality of fins projects from the container unit into the exit cavity such that the plurality of fins collides with counter-flow exhaust gas that counter-flows in a direction from the exit passage to the exit cavity through the first opening. The plurality of fins divides the exit cavity into a plurality of cavities, in which counter-flow exhaust gas forms a plurality of vortex flows.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with additional objectives, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawings in which:

FIG. 1 is a partial cross-sectional view illustrating a secondary air control valve according to the first embodiment of the present invention;

FIG. 2 is a plan view illustrating an interior of the secondary air control valve of the first embodiment; and

FIG. 3 is a plan view illustrating an interior of a secondary air control valve according to the second embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Multiple embodiments for executing the present invention will be described below with reference to accompanying drawings. In each of the embodiments, the components, which have been already described in the preceding embodiment, will be indicated by the same numerals, and the explanation thereof may be omitted. In a case, where only a part of the configuration is described in each of the embodiments, the explanation of the other part of the configuration employs the explanation described in the preceding embodiment. Parts of the components or configuration in the embodiments may be combined with each other as required even though the combination is not explicitly suggested in the description of the embodiments provided that the combination does not provide substantial difficulty.

First Embodiment

FIG. 1 is a partial cross-sectional view taken along lines 1-1 in FIG. 2 for illustrating a secondary air control valve according to the first embodiment of the present invention. FIG. 2 is a plan view illustrating an interior of the secondary air control valve of the first embodiment and is taken along lines II-II in FIG. 1 to observe in a direction from a valve mechanism to a second body.

A secondary air supply apparatus 1 supplies air to an exhaust system of an internal combustion engine. The internal combustion engine serves as a power source for a vehicle, an air conditioner, or a power generator. In the embodiment, the internal combustion engine is the vehicle that serves as a power source mounted on the vehicle. Air supplied to the exhaust system is referred to as secondary air. The secondary air oxides components in the exhaust gas. As a result, it is possible to improve the quality of exhaust gas components, or to refresh an exhaust gas processing apparatus, for example. The secondary air supply apparatus 1 introduces air to a position downstream of an air cleaner of an intake system 2. Air is pressurized by a pump. The secondary air supply apparatus 1 supplies secondary air to an exhaust system 3 located immediately downstream of the combustion chamber of the internal combustion engine. The secondary air supply apparatus 1 has a secondary air control valve 4 located between the intake system 2 and the exhaust system 3. The secondary air control valve 4 is capable of allowing and prohibiting the flow of secondary air, and further is capable of control an amount of secondary air as required. The secondary air control valve 4 is provided between the intake system 2 and the exhaust system 3 of the internal combustion engine. The secondary air control valve 4 is connected to the exhaust system 3, into which exhaust gas of the internal combustion engine flows, and supplies secondary air to the exhaust system 3. Furthermore, the secondary air control valve 4 is provided at a position, at which part of exhaust gas from the exhaust system 3 counter-flows (or flows back) toward the secondary air control valve 4.

The secondary air control valve 4 includes a passage forming member that defines a passage, through which secondary air is supplied to the exhaust system 3. The passage forming member includes a first body 5 and a second body 6. The first body 5 defines a passage for the intake system 2, and the second body 6 defines a passage for the exhaust system 3. A valve mechanism 7 is provided in the passage for secondary air defined by the first body 5 and the second body 6. the valve mechanism 7 has a motor-operated valve 71 and a check valve 75.

The first body 5 is also referred to as an upper body. The first body 5 includes an inlet pipe 51 connected to a piping, through which secondary air is introduced from the intake system 2. The first body 5 defines an inlet passage 52 and an intermediate passage 53 within the inlet pipe 51. The intermediate passage 53 is a cylindrical cavity. The first body 5 has a valve seat 54 located between the inlet passage 52 and the intermediate passage 53. The valve seat 54 defines a valve seat passage. The valve seat 54 also serves as a part of the motor-operated valve 71, which will be described later. The inlet passage 52 has a straight part and an elbow part. The straight part extends in an axial direction of the inlet pipe 51, and the elbow part curves generally at the right angle toward the intermediate passage 53. The valve seat 54 is provided coaxially to the intermediate passage 53. The inlet passage 52, the valve seat passage, and the intermediate passage 53 constitute an inlet cavity.

The first body 5 defines a receiving chamber that receives therein the motor-operated valve 71. The motor-operated valve 71 has a mushroom-shaped movable valve 72, a drive mechanism 73, and an electric motor 74. The movable valve 72 has a valve element and a shaft portion. The valve element is provided within the intermediate passage 53 and has a circular plate shape. The shaft portion extends from the valve element into the inlet passage 52. The drive mechanism 73 reciprocably actuates the movable valve 72 in the axial direction of the valve 72 based on the rotation of the motor 74. The drive mechanism 73 includes multiple gears and a reduction mechanism having a rack-and-pinion mechanism. The movable valve 72 moves in the axial direction between a valve closing position, at which the movable valve 72 is seated on the valve seat 54, and a valve opening position, at which the movable valve 72 is lifted away from the valve seat 54. Furthermore, it is possible to adjust a flow amount of secondary air when a lift amount, by which the movable valve 72 is lifted away from the valve seat 54, is adjusted, and thereby a passage cross-sectional area for secondary air is adjusted.

The check valve 75 is provided to cover the intermediate passage 53 of the first body 5. The check valve 75 allows a regular flow that is directed in a direction from the intake system 2 to the exhaust system 3. Also, the check valve 75 prohibits a counter flow that is directed in the other direction from the exhaust system 3 to the intake system 2. The check valve 75 has a supporting plate 76 and a reed valve 77. The supporting plate 76 is provided to cover an opening of the intermediate passage 53. The supporting plate 76 has a through hole that extends therethrough at a general center. The reed valve 77 is made of a spring steel. The reed valve 77 is provided at a position downstream of the through hole in the direction of the regular flow. The reed valve 77 is provided to completely cover the through hole. The reed valve 77 has one end that serves as a fixed end fixed to the supporting plate 76. Also, the reed valve 77 has the other end that serves as a free end displaceable to be lifted from the supporting plate 76. Furthermore, the supporting plate 76 has a stopper 78 that regulates a maximum lift amount of the reed valve 77.

The second body 6 is also referred to as a lower body. The second body 6 is provided at a position below the first body 5, and receives therein the check valve 75. The second body 6 defines a passage for secondary air at a position downstream of the valve mechanism 7. The second body 6 has a container unit 61, an exit pipe 63, and a supporting bracket 67. The container unit 61 has a tubular shape with a bottom. The exit pipe 63 extends from the container unit 61, and the supporting bracket 67 extends from the container unit 61. The exit pipe 63 is connected to the exhaust pipe of the exhaust system 3. The supporting bracket 67 is fixed to the internal combustion engine in order to support the secondary air control valve 4.

The container unit 61 of the second body 6 defines therein an exit cavity 62 between the valve mechanism 7 and the exhaust system 3. The exit cavity 62 is located downstream of the valve mechanism 7. The exit cavity 62 has a flat rectangular parallelepiped shape.

The container unit 61 has a tubular side wall 61 a and a bottom wall 61 b. The side wall 61 a has an opening at one end adjacent the valve mechanism 7, and the bottom wall 61 b is provided at the other end of the side wall 61 a. The side wall 61 a is a rounded rectangular tube. The side wall 61 a extends from the valve mechanism 7 in a longitudinal direction. The side wall 61 a has a longitudinal axis that is parallel to a longitudinal axis of the intermediate passage 53. Hereinafter, the axial direction of the side wall 61 a is referred to as a longitudinal direction. In other words, an up-down direction in FIG. 1 is referred to as the longitudinal direction.

The container unit 61 and the exit pipe 63 defines an exit passage 64 that has (a) a first opening 65 communicated with the exit cavity 62 and (b) a second opening 66 communicated with the exhaust system 3. The first opening 65 opens to the side wall 61 a. The first opening 65 opens on a side-wall side of a boundary line between the side wall 61 a and the bottom wall 61 b. The first opening 65 has a lower end that generally coincides with an inner surface of the bottom wall 61 b. The exit passage 64 is formed to have an axial line AX64 that is generally in parallel to the inner surface of the bottom wall 61 b. As a result, the inner surface of the bottom wall 61 b extends along an imaginary extension of the exit passage 64. Also, the exit passage 64 extends in a transverse direction to cross the longitudinal direction. Furthermore, the exit passage 64 is angled such that the exit passage 64 is displaced in a direction away from the valve mechanism 7 as a function of distance from the exit cavity 62.

In a plan view of FIG. 2, the exit passage 64 extends radially outwardly from the exit cavity 62 to be angled relative to the side wall 61 a. In other words, in the plan view, the axial line AX64 of the exit passage 64 generally extends along a tangential direction of an inscribed circle of the side wall 61 a.

An inner surface of the side wall 61 a adjacent the exit pipe 63 forms an inclined surface 61 d that is angled to face the opening of the container unit 61. The first opening 65 opens to the inclined surface formed on an inner surface of the side wall 61 a adjacent the exit pipe 63. The bottom wall 61 b is angled such that the bottom wall 61 b is located at a lower-most part of the first opening 65. The bottom wall 61 b is defined by two inclined surfaces that are slightly angled relative to each other. the two inclined surfaces cross each other to form a valley line 61 e that extends from the first opening 65 in a direction for crossing the exit cavity 62 as shown in the plan view of FIG. 2. As a result, the exit passage 64 extends downwardly from the lower-most part of the bottom wall 61 b in the inclined manner as shown in FIG. 1.

In the secondary air control valve 4, when the motor-operated valve 71 is opened, secondary air is supplied to the exhaust system 3. Secondary air flows in the order of the inlet passage 52, the motor-operated valve 71, the intermediate passage 53, the check valve 75, the exit cavity 62, the first opening 65, the exit passage 64, and the second opening 66. A flow FF of secondary air as above is referred to as the regular flow. In contrast, exhaust gas in the exhaust system 3 may counter-flow from the exit passage 64 into the exit cavity 62 through the first opening 65. The above exhaust gas that counter-flows is referred to as counter-flow exhaust gas. Counter-flow exhaust gas flows through the exit passage 64, and subsequently flows through the first opening 65 along the inner surface of the bottom wall 61 b into the exit cavity 62. The exit passage 64 and the first opening 65 are formed such that the above counter-flow exhaust gas is generated.

The second body 6 that serves as the passage forming member has multiple fins 8 that projects from the container unit 61 into the exit cavity 62. The multiple fins 8 may be referred to as inner fins. The fins 8 are provided such that the fins 8 collide with counter-flow exhaust gas. Also, the multiple fins 8 divide the exit cavity 62 into multiple small cavities (or small cavity segments). In other words, the multiple fins 8 defines multiple small cavities within the exit cavity 62. Specifically, the multiple fins 8 defines multiple small cavities within the exit cavity 62 such that counter-flow exhaust gas forms multiple vortex flows that are directed respectively to the small cavities. In the above configuration, exhaust gas counter-flows from the exit passage 64 into the exit cavity 62 through the first opening 65 of the exit passage 64. As above, the multiple fins 8 projects from the container unit 61 within the exit cavity 62. As a result, it is possible to enlarge the surface area that exchanges heat with counter-flow exhaust gas. Thus, it is possible to effectively remove heat from counter-flow exhaust gas. Furthermore, the multiple fins 8 cause counter-flow exhaust gas to form multiple vortex flows. As a result, it is possible to weaken the flow of counter-flow exhaust gas.

In the above, the fin 8 does not define a closed cavity by completely surrounding a certain space. The cavity defined by the fin 8 opens in the height direction of the side wall 61 a. Also, the cavity defined by the fin 8 opens through the opening, through which air flows into or out of the container unit 61. As above, in the present embodiment, if the fin 8 completely defines the space, the fin 8 extends from one part of the side wall 61 a to the other part of the side wall 61 a such that the fin 8 blocks the flow of air from one side to the other side of the fine 8 in the direction in parallel to the bottom wall 61 b, for example. However, for example, none of the fins 8 connects the one part with the other part of the side wall 61 a by crossing the exit cavity 62 as shown in FIG. 2. As a result, the definition by the fin 8 in the present embodiment is incomplete, and thereby it is appreciated that the cavity of the present embodiment is incompletely closed. In another point of view, a single fin 8 is configured to define the section such that there are flows of air in different directions on both sides of the single fin 8.

All of the fins 8 are connected to the bottom wall 61 b. The multiple fins 8 includes a connected fin 81 and a separated fin 82. The connected fin 81 is connected to both the side wail 61 a and the bottom wall 61 b. The separated fin 82 is connected only to the bottom wall 61 b, but is separate from the side wall 61 a. The connected fin 81 projects from the side wall 61 a into the exit cavity 62 like a jetty. As a result, the connected fin 81 and the side wall 61 a define a terminal cavity, a radially-outward end of which is closed. The separated fin 82 is formed as an island within the exit cavity 62 separately from the side wall 61 a. As a result, the separated fin 82 defines an annular cavity around the separated fin 82. In the above configuration, counter-flow exhaust gas flows in a complicated manner due to collision with the connected fin 81 and the separated fin 82, and thereby the flow of counter-flow exhaust gas is effectively weakened.

All of the fins 8 are plate members that project from the bottom wall 61 b in the longitudinal direction, or in other words project in the height direction of the side wall 61 a. Also, all of the fins 8 are plate members that are configured by surfaces that include straight line extending in the longitudinal direction. As a result, all of the fins 8 divide the exit cavity 62 into multiple small sections arranged in the transverse direction, but do not divide the exit cavity 62 into multiple small sections arranged in the longitudinal direction. Furthermore, all of the fins 8 are flat plates.

All of the fins 8 have heights that are smaller than the height of the side wall 61 a. In other words, all of the fins 8 have edges adjacent the valve mechanism 7 that are positioned at a level that is similar to the level of the side wall 61 a in the height direction. As a result, an unfinned cavity 62 a, which is not provided with fins, is formed between the multiple fins 8 and the valve mechanism 7. The unfinned cavity 62 a extends along the opening of the side wall 61 a. In other words, as shown in the cross-sectional view, the exit cavity 62 includes a first half cavity segment 62 a, which is located adjacent the valve mechanism 7, and a second half cavity segment 62 b, which is located adjacent the bottom wall 61 b. The first half cavity segment 62 a adjacent the valve mechanism 7 is the unfinned cavity 62 a. The second half cavity segment 62 b adjacent the bottom wall 61 b may be referred to as a finned cavity 62 b having therein the multiple fins 8. The unfinned cavity 62 a and the finned cavity 62 b are communicated with each other without any obstacle in the height direction of the side wall 61 a. Air is movable without any obstacle within the unfinned cavity 62 a in a direction perpendicular to the longitudinal direction, or in other words, in a direction generally parallel to the bottom wall 61 b. However, flow of air is regulated within the finned cavity 62 b in the direction perpendicular to the longitudinal direction because the multiple fins 8 are in the way of flow of air. The entirety of the first opening 65 is positioned to face the finned cavity 62 b.

In the above configuration, secondary air, which flows into the exit cavity 62 through the valve mechanism 7, reaches the first opening 65 of the exit passage 64 via the unfinned cavity 62 a and the finned cavity 62 b. As a result, when secondary air flows inside the unfinned cavity 62 a, secondary air does not collide with the fins 8. Furthermore, because the fin 8 projects in the height direction of the side wall 61 a, secondary air, which flows into the exit cavity 62 through the valve mechanism 7, flows along the fin 8 in the height direction of the side wall 61 a. Thereby, it is possible to weaken the flow of counter-flow exhaust gas without excessively increasing the resistance to the regular flow of secondary air.

The multiple fins 8 are generally radially provided within the exit cavity 62 when observed in the plan view. The above configuration provides low resistance to the regular flow of secondary air that is caused to flow in the exit cavity 62 in the longitudinal direction. In contrast, the above configuration provides high resistance to flow of counter-flow exhaust gas that is caused to swirl along the side wall 61 a within the exit cavity 62.

The multiple fins 8 includes multiple terminal sectioning fins 81 a, 81 b, 81 c, 81 d. All of the terminal sectioning fins 81 a, 81 b, 81 c, 81 d are the connected fins 81. The terminal sectioning fins 81 a, 81 b, 81 c, 81 d divide the interior space of the exit cavity 62 into multiple terminal cavities. Furthermore, the terminal sectioning fins 81 a, 81 b, 81 c, 81 d divide flow of counter-flow exhaust gas into multiple flows that are directed to the corresponding multiple terminal cavities. The terminal sectioning fins 81 b, 81 c, 81 d are radially provided within the exit cavity 62. The terminal sectioning fin 81 a is provided generally in parallel to an axial line of the exit passage 64. In the above configuration, counter-flow exhaust gas is divided into multiple flows that are directed to the respective multiple terminal cavities. As a result, it is possible to effectively weaken the flow of counter-flow exhaust gas.

The multiple fins 8 include obstacle fins 82 a, 82 b. The obstacle fins 82 a, 82 b are provided on an imaginary extension of the exit passage 64 such that the obstacle fins 82 a, 82 b directly collide with counter-flow exhaust gas. The obstacle fins 82 a, 82 b divide counter-flow exhaust gas into at least a first flow R1 and a second flow R2. The obstacle fin 82 a is provided to extend along the side wall 61 a. The obstacle fins 82 a, 82 b bend the first flow R1 of counter-flow exhaust gas in a direction generally right angle relative to the axial line AX64 of the exit passage 64. The obstacle fin 82 a causes the second flow R2 of counter-flow exhaust gas to flow along the side wall 61 a. In the above configuration, because counter-flow exhaust gas directly collides with the obstacle fins 82 a, 82 b, it is possible to effectively weaken the flow of counter-flow exhaust gas. Furthermore, counter-flow exhaust gas is divided into multiple flows that include at least the first flow R1 and the second flow R2. As a result, it is possible to effectively weaken each of the divided multiple flows.

The multiple fins 8 include a guide fin 82 c. The guide fin 82 c is provided on an imaginary extension of the obstacle fins 82 a, 82 b. The guide fin 82 c causes the second flow R2 to flow along the side wall 61 a.

The multiple fins 8 further include a center sectioning fin 82 e that defines a first cavity and a second cavity within the exit cavity 62. In the plan view, a right half of the exit cavity 62 corresponds to the first cavity, and a left half corresponds to the second cavity. The first flow R1 is mainly introduced to the first cavity. The second flow R2 is mainly introduced to the second cavity. It should be noted that the obstacle fins 82 a, 82 b also define the first cavity and the second cavity within the exit cavity 62 when observed from the first opening 65. There is formed a clearance between the center sectioning fin 82 e and the obstacle fin 82 b. The clearance allows part of counter-flow exhaust gas to flow therethrough. In the above configuration, the center sectioning fin 82 e incompletely defines the first cavity and the second cavity within the exit cavity 62. As a result, it is possible to effectively weaken each of the divided multiple flows R1, R2.

Alternatively, the center sectioning fin 82 e may completely defines the first cavity and the second cavity within the exit cavity 62 by connecting one part of the side wall 61 a with the other opposing part of the side wall 61 a, for example.

The multiple fins 8 include vortex flow guide fins 82 d, 82 f, 82 g, 82 h that are provided as islands within the exit cavity 62. In the present specification, the term “fin provided as an island” indicates that the fin is provided separate from the side wall 61 a. The vortex flow guide fins 82 d, 82 f, 82 g, 82 h define annular cavities that cause counter-flow exhaust gas to form vortex flow around the vortex flow guide fins 82 d, 82 f, 82 g, 82 h. In the above configuration, there is formed at least one vortex flow guide fin 82 d, 82 f, 82 g, 82 h, which is provided as the island, within the exit cavity 62. As a result, there is formed the annular cavity around the vortex flow guide fin 82 d, 82 f, 82 g, 82 h. At least part of counter-flow exhaust gas forms the vortex flow in the annular cavity. Therefore, it is possible to effectively weaken counter-flow exhaust gas within the exit cavity 62.

The terminal sectioning fins 81 a, 81 b, 81 c, 81 d include (a) first terminal sectioning fins 81 a, 81 b, which are provided within the first cavity, and (b) second terminal sectioning fins 81 c, 81 d, which are provided within the second cavity. In the above configuration, the first flow R1 is divided into multiple flows that are directed respectively to the multiple terminal cavities. As a result, it is possible to effectively weaken the first flow R1. Also, the second flow R2 is divided into multiple flows that are directed respectively to the multiple terminal cavities. As a result, it is possible to effectively weaken the second flow R2.

It should be noted that the exit cavity 62 may be referred to as a main cavity. The first cavity and the second cavity may be referred to as sub-cavities formed by dividing the main cavity. Furthermore, sub-cavities are classified into (a) center cavities, which are located at a general center, and (b) multiple terminal cavities, which are provided along the side wall 61 a.

The vortex flow guide fins 82 d, 82 f, 82 g, 82 h include the first vortex flow guide fin 82 d, which is provided as the island in the first cavity, and the second vortex flow guide fins 82 f, 82 g, 82 h, which are provided as the islands in the second cavity. In the above configuration, at least part of the first flow R1 forms a vortex flow S1 in the first cavity. Thereby, it is possible to effectively weaken the first flow R1 in the first cavity. Also, at least part of the second flow R2 forms a vortex flow 52 in the second cavity. Furthermore, multiple vortex flows are formed in the second cavity. Thereby, it is possible to effectively weaken the second flow R2 in the second cavity.

Furthermore, the first vortex flow guide fin 82 d is provided between the two terminal sectioning fins 81 a, 81 b. As a result, it is possible to effectively weaken the flow of counter-flow exhaust gas in the terminal cavity. Furthermore, the second vortex flow guide fins 82 f, 82 g, 82 h are provided between the two terminal sectioning fins 81 c, 81 d. As a result, it is possible to effectively weaken the flow of counter-flow exhaust gas in the other terminal cavity.

The check valve 75 of the valve mechanism 7 defines a valve passage 77 a that allows secondary air to flow toward the exit cavity 62. The valve passage 77 a is formed when the reed valve 77 is opened. As a result, the valve passage 77 a is oriented in a direction along the slanted reed valve 77. As shown in the cross-sectional view of FIG. 1, the reed valve 77 has the free end on a left side of the exit cavity 62. As a result, the valve passage 77 a defined by the reed valve 77 opens in the left side of the exit cavity 62. Furthermore, the valve passage 77 a extends in a direction from the upper side to the lower side of the exit cavity 62, and is oriented from a center in a left direction in a slanted manner. The multiple fins 82 f, 82 g, 82 h are positioned on the imaginary extension of the valve passage 77 a. The multiple fins 821, 82 g, 82 h extend in a left-right direction of the exit cavity in the plan view of FIG. 2. In other words, the multiple fins 82 f, 82 g, 82 h form along an imaginary extension of the valve passage 77 a. For example, the imaginary extension of the valve passage 77 a spread radially outwardly from the opening of the reed valve 77 to form a flared passage shape. In the present embodiment, because the multiple fins 82 f, 82 g, 82 h form along the imaginary extension of the valve passage 77 a, the collision of the regular flow FF of secondary air with the fins 82 f, 82 g, 82 h is effectively suppressed. In other words, because the multiple fins 82 f, 82 g, 82 h form to extend in a radial direction of the second body 6 along the regular flow FF of secondary air that flows through the valve passage 77 a, the collision of the regular flow FF of secondary air with the fins 82 f, 82 g, 82 h is effectively suppressed. As a result, without excessively increasing resistance to the regular flow of secondary air, it is possible to effectively weaken the flow of counter-flow exhaust gas.

Multiple outer fins 68 are formed on an outer surface of the container unit 61. The multiple outer fins 68 have plate shapes and extend in a direction perpendicular to a cross section shown in the cross-sectional view of FIG. 1. The multiple outer fins 68 are provided in a range from the container unit 61 to the exit pipe 63. The multiple outer fins 68 are provided in parallel to each other and are spaced apart from each other. Each of the outer fins 68 is provided in parallel to the flow of cooling air that flows around the secondary air control valve 4. Due to the above configuration, it is possible to effectively cause counter-flow exhaust gas to dissipate heat to the exterior of the container unit 61 and the exit pipe 63.

In the above embodiment, it is possible to effectively remove heat from counter-flow exhaust gas. Furthermore, it is possible to effectively weaken the flow of counter-flow exhaust gas. Furthermore, it is possible to effectively weaken the flow of counter-flow exhaust gas without excessively increasing resistance to the regular flow of secondary air. Furthermore, it is possible to achieve the above advantages with a simple configuration. As a result, it is possible to provide a secondary air control valve that is protected from adverse effect of counter-flow exhaust gas.

Second Embodiment

FIG. 3 is a plan view illustrating an interior of a secondary air control valve according to the second embodiment of the present invention, and is a plan view, in which a second body 206 is observed from the valve mechanism 7. In the present embodiment, multiple fins 8 have shapes different from the shapes in the first embodiment.

Fins 281 a, 281 b, 281 c, 282 a, 282 b, 282 c, 282 d, 282 e, 282 f of the present embodiment have shapes, positions, and functions that correspond to those of the fins 81 a, 81 b, 81 c, 82 a, 82 b, 82 c, 82 d, 82 e, 82 h, respectively. In the embodiment, terminal sectioning fins 281 d, 281 e are provided instead of the vortex flow guide fins 82 f, 82 g of the first embodiment. Also, a vortex flow guide fin 282 g is provided instead of the terminal sectioning fin 81 d. Due to the above configuration, it is also possible to achieve the similar advantages that are achievable in the first embodiment.

Other Embodiment

In the above, embodiments of the present invention have been described. However, the present invention is not limited to the above embodiments, and thereby the present invention is applicable to various modifications provided that the modifications do not deviate from the gist of the present invention. The structures in the above embodiments are merely examples, and thereby the scope of the present invention is not limited to the scope of the description in the above embodiments. The scope of the present invention is defined by the description in claims, and thereby the scope of the present invention further includes all the modifications included by and equivalent to the description of claims.

For example, all the multiple fins may alternatively be the connected fins. Also, alternatively, all the multiple fins may be the separated fins. Also, the obstacle fin may be configured to divide counter-flow exhaust gas into three or more flows. Furthermore, the multiple fins 8 may be alternatively formed by curved plates.

Additional advantages and modifications will readily occur to those skilled in the art. The invention in its broader terms is therefore not limited to the specific details, representative apparatus, and illustrative examples shown and described. 

1. A secondary air control valve connected to an exhaust system, which allows exhaust gas to flow therethrough, wherein the secondary air control valve supplies secondary air to the exhaust system, the secondary air control valve comprising: a passage forming member that defines a passage, through which secondary air is supplied to the exhaust system; and a valve mechanism provided in the passage, wherein: the passage forming member includes: a container unit that defines therein: an exit cavity provided between the valve mechanism and the exhaust system; and an exit passage having a first opening communicated with the exit cavity and having a second opening communicated with the exhaust system; and a plurality of fins that projects from the container unit into the exit cavity such that the plurality of fins collides with counter-flow exhaust gas that counter-flows in a direction from the exit passage to the exit cavity through the first opening, the plurality of fins dividing the exit cavity into a plurality of cavities, in which counter-flow exhaust gas forms a plurality of vortex flows.
 2. The secondary air control valve according to claim 1, wherein: the plurality of fins includes an obstacle fin that is provided on an imaginary extension of the exit passage such that the obstacle fin directly collides with counter-flow exhaust gas; and the obstacle fin divides counter-flow exhaust gas into at least a first flow and a second flow.
 3. The secondary air control valve according to claim 2, wherein: the plurality of fins further includes a center sectioning fin that defines a first cavity, into which the first flow is mainly introduced, and a second cavity, into which the second flow is mainly introduced, within the exit cavity.
 4. The secondary air control valve according to claim 3, wherein: the plurality of fins includes: a first vortex flow guide fin that is provided as an island within the first cavity, the first vortex flow guide fin defining therearound an annular cavity that causes counter-flow exhaust gas to form a vortex flow; and a second vortex flow guide fin that is provided as an island within the second cavity, the second vortex flow guide fin defining therearound an annular cavity that causes counter-flow exhaust gas to form a vortex flow.
 5. The secondary air control valve according to claim 4, wherein: the plurality of fins includes: a first terminal sectioning fin that defines a plurality of terminal cavities within the first cavity, the first terminal sectioning fin dividing the first flow into a plurality of flows directed respectively to the plurality of terminal cavities; and a second terminal sectioning fin that defines a plurality of terminal cavities within the second cavity, the second terminal sectioning fin dividing the second flow into a plurality of flows directed respectively to the plurality of terminal cavities.
 6. The secondary air control valve according to claim 1, wherein: the plurality of fins includes a vortex flow guide fin that is provided as an island within the exit cavity; and the vortex flow guide fin defines therearound an annular cavity that causes counter-flow exhaust gas to form a vortex flow.
 7. The secondary air control valve according to claim 1, wherein: the plurality of fins includes a plurality of terminal sectioning fins that defines a plurality of terminal cavities within the exit cavity; and the plurality of terminal sectioning fins divides counter-flow exhaust gas into a plurality of flows that flows directed respectively to the plurality of terminal cavities.
 8. The secondary air control valve according to claim 1, wherein: the container unit includes: a tubular side wall having an opening at one end adjacent the valve mechanism; and a bottom wall provided at the other end of the side wall; the container unit defines therein the exit passage and the first opening such that counter-flow exhaust gas flows into the exit cavity along an inner surface of the bottom wall; and the plurality of fins includes: a connected fin connected to both the side wall and the bottom wall and projecting from the side wall; and a separated fin connected only to the bottom wall and separate from the side wall.
 9. The secondary air control valve according to claim 8, wherein: each of the plurality of fins has a plate shape that projects from the bottom wall in a direction of a height of the side wall; each of the plurality of fins has a height smaller than the height of the side wall; and the exit cavity includes a cavity segment defined between the plurality of fins and the valve mechanism and extending along the opening of the side wall.
 10. The secondary air control valve according to claim 1, wherein: the valve mechanism defines a valve passage that allows the secondary air to flow therethrough into the exit cavity; the plurality of fins includes a fin located at a position on an imaginary extension of the valve passage; and the fin forms along the imaginary extension of the valve passage.
 11. The secondary air control valve according to claim 1, wherein the container unit has a plurality of outer fins formed on an outer surface thereof. 